The present invention relates to facsimile systems and, more particularly, to apparatus for answering an incoming call over a single telephone line and for automatically switching the call between a telephone and a carrier signal-based device as appropriate comprising, three position switch means for switching a telephone line connected thereto between first, second and third output positions thereof, the switch means having the telephone operably connected to the second output position thereof and the carrier signal-based device connected to the third output position thereof; first logic means having an input connected to the first output position of the switch means and an output operably connected to switch the switch means between the first, second and third output positions for answering an incoming call on the telephone line, for determining whether the incoming call is from a carrier signal-based device, for switching the switch to connect the second output position when an incoming call from a non-carrier signal-based device is detected, and for switching the switch to connect the third output position when an incoming call from a carrier signal-based device is detected; and, second logic means having an input connected to sense transmissions from the telephone and the carrier signal-based device and an output operably connected to switch the switch means between the first, second and third output positions for switching the switch to the first position when a hang up by the telephone or the carrier signal-based device is detected.
Facsimile (FAX) machines are rapidly growing in popularity as they become cheaper and cheaper. One of the target groups for future development and sales is the so-called "low end user", e.g. home offices, small businesses, and individuals for personal and business use. The preferred method for installation at a particular site is shown in FIG. 1 wherein the telephone 10 has one telephone line 12 connected to it and the FAX machine 14 has a second telephone line 12' connected to it. While this gives preferred operation for both the telephone 10 and the FAX machine 14 by preventing interference between the two devices, it is expensive for the low end user who may only use the FAX machine 14 occasionally and cannot justify the installation and monthly costs of a separate telephone line for the FAX machine. The same is true for other types of devices which employ telephone lines for data transmission, such as modems operating with computers.
In instances where the user does not wish to install a separate telephone line for the FAX machine, or the like, the typical prior art options are depicted in FIGS. 2 and 3. As shown in FIG. 2, the telephone 10 and FAX machine 14 are connected to a single telephone line 12 through a Y-connector 16 which places the two devices in parallel. Outgoing use of either the telephone 10 or FAX machine 14 is easy with this arrangement; however, the FAX machine 14, being automatic in its operation when turned on, will tend to grab all the incoming calls. For that reason, as shown in FIG. 3, the telephone 10 and FAX machine 14 are more commonly connected to a single telephone line 12 through a switch 18 which allows the user to select which of the devices is connected to the common telephone line 12 at any time. When the user wants to use the FAX machine 14 (and at night when unattended), it is switched to the telephone line 12. The rest of the time, the telephone 10 is connected through the switch 18. As can be appreciated, this arrangement has many shortcomings as well. If one wants to receive incoming FAX transmissions when out of the office, it is impossible to have a telephone answering machine to receive incoming telephone calls. Moreover, during the daytime when the office is attended and the switch 18 has the telephone 10 connected to the telephone line 12, anyone wishing to send a FAX transmission must first call on the telephone 10 and advise the user to switch to the FAX position.
Wherefore, it is the object of the present invention to provide a simple and easy modification for FAX machines and their method of operation which will allow telephones and FAX machines to actively share a common telephone line with the proper device answering incoming calls.
It is another object of the present invention to provide a simple and easy modification for FAX machines and their method of operation which will allow telephones and FAX machines to actively share a common telephone line with the ability for the telephone to employ an answering machine in conjunction therewith whereby both incoming FAX reception and incoming message recording can be accomplished in an unattended state.
Other objects and advantages of the present invention will become apparent from the description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.